ELECTRON-CYCLOTRON HEATING COMBINED WITH LOWER-HYBRID CURRENT DRIVE ON WT-3

Lower hybrid current drive (LHCD) is applied to improve the confinemen t in the WT-3 tokamak. With increasing the lower hybrid (LH) power, a sharp decrease in electron thermal diffusivity chi(e) is observed at a certain LH power. The chi(e) is directly measured by applying the sim ple time-to-peak method to propagation of a heat pulse induced by a sh ort electron cyclotron heating (ECH) pulse. A high electron temperatur e is obtained by applying ECH to the LHCD plasma with improved chi(e). The efficiency of ECH in the LHCD plasma with improved chi(e) becomes three times that in ohmic heating plasmas.